A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity
Open-File Report
78-669
By: James Henry Scott
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Abstract
The FORTRAN algorithm described in this report was developed for applying corrections to normal resistivity logs of any electrode spacing for the effects of drilling mud of known resistivity in boreholes of variable diameter. The corrections are based on Schlumberger departure curves that are applicable to normal logs made with a standard Schlumberger electric logging probe with an electrode diameter of 8.5 cm (3.35 in). The FORTRAN algorithm has been generalized to accommodate logs made with other probes with different electrode diameters. Two simplifying assumptions used by Schlumberger in developing the departure curves also apply to the algorithm: (1) bed thickness is assumed to be infinite (at least 10 times larger than the electrode spacing), and (2) invasion of drilling mud into the formation is assumed to be negligible.
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Suggested Citation
Scott, J.H., 1978, A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity: U.S. Geological Survey Open-File Report 78-669, 12 leaves ;27 cm.; (13 p. - PGS), https://doi.org/10.3133/ofr78669.
ISSN: 2331-1258 (online)
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity |
| Series title | Open-File Report |
| Series number | 78-669 |
| DOI | 10.3133/ofr78669 |
| Year Published | 1978 |
| Language | ENGLISH |
| Publisher | U.S. Geological Survey, |
| Description | 12 leaves ;27 cm.; (13 p. - PGS) |